The present invention relates to an intramedullary awl assembly for opening bone tissue of a patient's femur, in preparation for an ensuing procedure, as to install an intramedullary nail in the femur.
Intramedullary awls are known and serve to open the bone in order then to be able to effect a femoral-style nailing in which a stainless steel nail, having for instance a clover-leaf or U-shaped cross section, can be inserted into the medullary cavity under control of an X-ray, for example, in the case of a fracture of a long bone. Before insertion of the nail, the medullary cavity situated in the middle two-thirds of the femur bone is opened by a drill or reamer. Before insertion of the reamer, it is necessary that the bone be first provided with a corresponding opening by means of an awl at the proximal end of the bone. Thereafter, in connection with insertion of the reamer, a guide wire for guiding the medullary reamer can be inserted through this opening. The opening in the bone produced by the awl is in coaxial alignment with the longitudinal axis of the medullary cavity in the region of the fossa between the greater trochanter and femoral head.
In DE-U 89 14 852 there is described an intramedullary awl which consists of two tools, namely, the awl and a guide tool. The guide tool has a receiving socket by which the working tip of the intramedullary awl can be guided. The receiving socket with the tip of the intramedullary awl is introduced into the hollow space between the greater trochanter and femoral head, bounded in part by the femoral neck, enabling the receiving socket to provide directional support for the awl to puncture the wall of the bone and enter its interior beneath the wall of the bone. After removal of the intramedullary awl from the opening in the bone produced by it, the receiving socket may remain in the hollow space between the greater trochanter and femoral head so that the patient's adjacent musculature does not again close the opening. In this way, easy introduction of the guide wire for the intramedullary reamer is made possible.
One problem in the case of the known tools is that an exact alignment of the actual guidance or orienting support for the working tip of the intramedullary awl is difficult. Such alignment is necessary since the intramedullary awl preferably passes through the bone precisely along and in coaxial alignment with the longitudinal axis of the medullary cavity in order thereby to obtain a guidance reference that is aligned with the medullary cavity in that such a guidance reference is needed for insertion of the guide wire and also for use of the drill or reamer tooling which is to expand the bore in the bone to a size which will accept insertion of an intramedullary nail.